The CC 13 is a modular charging and transport case. The basic version consists of a cover (CT 10), a charging unit (CD 13) for 12 MCW-D 531 / MCW-D 533 microphone units and a bottom with casters (CW 10). The MCW-D 50 discussion control unit can be accomodated in an empty compartment (CS 10). Each charging unit has 12 compartments for the microphone units. On both sides there are handles for comfortable carrying. It is recommended to use not more than two CD 13 charging units on top of each other, because the top might become too heavy. The body of the case is made of plywood with a washable foil inside and grey laminate outside. The coloured surface is flecked with grey. The case is equipped with ball bearing casters with a diameter of 80 mm. Two of the casters are equipped with brakes. Silver anodised aluminium profiles protect the edges from shocks and ensure an exact fitting of the individual sections. There are four locking chromium-plated automatic locks per section. For charging the MCW-D 531 / MCW-D 533 microphone units are put into the charging facilities. Shock-mounted charging contacts ensure the electric connection between microphone unit and power supply unit. All batteries are charged simultaneously. After approximately 3.5 hours the battery is fully charged, depending on the previous use. The charging state of the batteries is indicated by the lateral LED strip of the microphone and can be seen from the outside through a window or when the cover is opened. To avoid a self-discharge of the batteries, trickle charging is carried out. So each microphone unit has its full capacity at any time. Therefore, beyerdynamic recommends the charger being connected to the mains permanently.